Only it’s more than going ‘bump’. Traumatised travellers have been reporting strange encounters on their morning commute, with strangely dressed people trying to deliver an urgent message.

Stranger still, despite calling the police themselves, within a few minutes the commuters have already forgotten the encounter - making the follow up interviews rather difficult.

So with a little help from Abigail and Toby the ghost hunting dog, Peter and Jaget are heading out on a ghost hunting expedition.

Because finding the ghost and deciphering their urgent message might just be a matter of life and death.

Born and raised in London, Ben Aaronovitch now lives in Kentish Town. He is a former bookseller and scriptwriter, most famously for Doctor Who when he was the first person to write a scene of a Dalek going up a flight of stairs in a TV story in ‘Remembrance of the Daleks’. He now writes full-time.